Journal of Construction Engineering and Management

This paper presents a decision support system for the evaluation of geologic exploration programs in underground construction. This system can be used to quantify the economic value of different subsurface investigation alternatives, and it provides owners and designers with a solid basis for making the associated technical and financial decisions. The description of the system includes the methodology for encompassing all the existing geologic information about a site in a consistent geologic‐prediction model that can be used for design, and construction, planning and estimation. It illustrates how to account for the context and reliability of this information, how to predict its effect on design and construction decisions, and how to arrive at a monetary measure of its value. Finally, it describes the methodology for using simulation to arrive at an estimate of the expected value and the standard deviation of the value of sampled geologic information. The evaluation of a pilot tunnel as an exploration alternative for the water discharge tunnel of the Seabrook Power station is presented as an example application.

AS the I‐595 Port Everglades Expressway program matured from the design stage to commencement of construction, the organization structure changed as well. The Florida Department of Transportation's innovative use of a construction services consultant (CSC) for an interstate highway program has evolved, from delegation of responsibility to the CSC from a few senior FDOT preconstruction/design managers, to the institution of a FDOT task force with project‐specific managers over the major functional areas of design, construction and right‐of‐way. The CSC has assumed a staff function with most of the responsibility and authority vested in the FDOT task force personnel. This arrangement works very well, improving communications within the Department, speeding approvals and leveraging the effectiveness of FDOT managers by the use of CSC staff experience in mega‐project management. A byproduct of using the readily mobilized CSC staff is the exposure of FDOT personnel to the latest microcomputer‐based management controls systems.

Recent CII research has indicated that formal material management programs have the potential to yield significant construction cost savings, yet small‐ and medium‐sized commercial contractors may not feel that an integrated material management program is cost effective. The objective of this paper is to quantify the adverse impacts of ineffective material management practices. Data collected as part of an ongoing construction productivity study is used to analyze and compare the effects of material management practices on two steel erection projects. Rules of credit were applied to calculate the daily output. Adverse conditions caused by the lack of an effective material management program are identified, and the days on which the conditions occurred are noted. For these days, the actual daily productivity is compared with the expected productivity to determine the number of work‐hours lost. The cost impact is compared to the cost of effective material management. The results show a benefits/cost ratio of 5.7, favoring greater attention to material management.

Several troublesome challenges face the U.S. construction industry: productivity is down, litigation is up, delays are common and expensive, foreign firms are taking a greater share of the market. The reasons are complex, but one important common factor is quality—or rather, the lack of it. In view of these facts, a quality performance tracking system (QPTS) has been developed to provide for the quantitative analysis of certain quality‐related aspects of projects, by systematically collecting and classifying costs of quality. By defining quality as “conformance to requirements,” the cost of quality becomes measurable. It consists of two main parts, the cost of quality management efforts and the cost of correcting deviations. A total of 15 categories identify the main quality management efforts. When coupled with 24 deviation categories (plus six “repeat” quality management categories), most of the important quality costs can be identified for tracking and analysis. These categories can be easily changed and adapted to meet individual company requirements for design, construction, and start‐up.

This paper concerns resources scheduling using a simple heuristic model described as the “current float” model. Current sfloat is defined as the finish float available with respect to its latest finish time in the original network computations. The current float model allocates limited resources by giving priority to the activity that has the least current float. The current floats need be computed only for those activities that are engaged in a resource conflict. The “total float” models that were used previously required the tedious task of constructing and computing a status network every time an activity is postponed due to nonavailability of resources. The current float model avoids this and requires only the original network computations. The mathematical validity of the model is explained, and the paper presents proof that the output of this model is the same as that of the total float model. The physical significance of the model is also indicated. An application section is included to illustrate the working of the model.

Piping commonly makes up 20–30% of the installed cost of a process plant. The prospects for making piping erection a repetitive, efficient process create a new demand for powerful, specialized pipe erection equipment. A pipe manipulator has been developed which is an adapation of a 20 ton rough terrain hydraulic crane, consisting of an attachment to the main boom. This paper explores desirable enhancements to the pipe manipulator to allow for increased automation, with an emphasis on fully automatic manipulator desirable new features. Three prime issues are discussed: msanagement of the local state of the manipulator arm, with incremental development of an arm motion control system; management of the global state of the manipulator, with a large scale manipulator metrology system; and navigation in a construction environment.

Construction on the first commercial nuclear power plant began in the early 1950s. Since that time, over 100 commercial nuclear generating units have been constructed and licensed to operate by the Atomic Energy Commission/Nuclear Regulatory Commission. This massive construction program over the last three and a half decades has generated many lessons to be learned by the civil engineering profession. This paper discusses the positive influences that nuclear construction continues to have on the construction industry.

Construction incentives can be useful devices to improve project performance. The use of schedule‐based incentives is particularly attractive because it can result in substantial time and cost savings. Furthermore, the design and implementation of schedule‐based incentives are relatively easy and inexpensive. They are especially applicable to projects for which timely completion is critical. Several different forms and combinations of schedule incentives are available, each having its own advantages. Schedule‐based incentive targets vary from the simplistic, end‐of‐project types, to the more sophisticated intermediate milestones, with various combinations in between. Both bonus and bonus/penalty award schemes are used in a wide array of forms. Contractor participation in the development of schedule targets can enhance the chances for success of the incentive plan, yet such participation is not always sought by owners. Use of bonus‐only schedule incentives is recommended whenever a perceived benefit from above average schedule performance exists. Bonus size should be substantial enough to capture the atten‐tion of the contractor's upper management. Exclusive use of penalties is counter‐productive.

Investigations are carried out on two concrete wall placements each 20.5 ft high, with thicknesses of 5 ft and 4 ft, respectively, to determine the loads and pressures exerted by the fresh concrete on the forms. Form tie forces are measured at intervals during the concrete placement, by instrumenting form ties with electrical resistance strain gages. Concrete pressures on the forms are determined from these forces by using the respective tie tributary areas. Maximum pressures of 1,062 psf for Wall I and 891 psf for Wall II are measured. The pressure influencing variables such as concrete density, mix design, admixtures, slump, stiffening time of concrete, concrete temperature, pour rate, consolidation method, and formwork dimensions are determined and used in comparing the measured wall pressures. Comparisons are also made between field results and currently recommended and proposed procedures for estimating wall form pressure.

In this paper a procedure is presented which provides a method to quantify work progress on construction projects. The procedure employs two management concepts, the work breakdown structure and the earned value. Although the theoretical basis for the proposed procedure is not new to the industry, it provides professional construction managers and project managers with a practical implementation of these concepts. The procedure is also an excellent computer application in construction management that requires only minimum programming skills. Examples of the input data file and output reports from an actual project are provided for numerical illustration.

This paper describes the typical pragmatic approach that construction planners taken in performing time‐cost trade‐off (TCT). In general, projects have major dominant characteristics, operations, or resources whose planning affects or dominates planning of other operations and resources. Planning focuses first on the dominant characteristics and is then fine‐tuned in its details. Planners typically cycle between plan generation and cost estimating at ever finer levels of detail until they settle on a plan that has an acceptable cost and duration. Computerized TCT methods do not follow this cycle. Instead, they separate the plan into activities, each of which is assumed to have a single time‐cost curve in which all points are compatible and independent of all points in other activities' curves and that contains all direct cost differences among its methods. In general, these assumptions are not true for construction. Construction activities are related because they share methods and resources. Crashing activities usually require changes from normal, least‐cost methods and resources. Changes in one activity are not independent of changes in related activities. Therefore, normal computerized TCT techniques are conceptually wrong for construction and they are not useful in practice.